These files include data and estimation code for:

Matthews, Abigail A. and Frederick J. Boehmke. N.d. "Researchers in the 
Laboratories of Democracy: A Quarter Century of Innovations in Studying 
Policy Diffusion in State Politics & Policy Quarterly" State Politics 
& Policy Quarterly (forthcoming). 

Compiled on January 8, 2026 by Frederick J. Boehmke (frederick-boehmke@uiowa.edu).


INCLUDED:  

2 Excel files: 
 
  mb2026sppq.xlsx                         Contains the SPPQ articles on  
                                          diffusion we included.
  mb2026sppq-otherjournals-counts.xlsx    Counts of diffusion articles from
                                          other journals.

2 text files: 
 
  mb2026sppq-stopwords.txt                Additional diffusion-related stopwords
                                          for the word clouds.

  mb2026sppq-otherjournals-searches.txt   Searches used to count total and 
                                          diffusion-related articles in select
                                          other journals. 

1 Stata do-file:  
 
  mb2026sppq.do                           Create the figures reported in the  
                                          paper.
  
1 pdf codebook file: 
  
  mb2026sppq-variables.pdf                Lists the included data sets with 
                                          information about variables.  

1 README file: 
  
  mb2026-README.txt                       Describes the included data and 
                                          files.  

  
NOTES:

1. The primary data set, mb2026sppq.xlsx, contains the information 
     needed to replicate the three figures reported in the paper generated 
     from our collection and coding of diffusion and diffusion-related articles 
     appearing in print or in advance view in SPPQ from 2000-2025. 
     
2. The supplemental data set, mb2026sppq-otherjournals.xlsx, is 
     used to calculate related information about diffusion articles published in 
     selected other journals.

3. The text file, mb2026sppq-stopwords.txt, contain a list of 
     additional stop words related to diffusion that we added when creating the 
     word clouds.
     
4. The tables and figures based on the SPPQ articles are created by 
     mb2026sppq.do. 

5. The programs are written for Stata version 17 or above, though they may run in 
     previous versions. 
     
6. The wordclouds were generated at voyant-tools.org based on the abstracts of
     the included articles. Sort the excel file by the category column and then 
     copy and paste the text of the abstracts into the "Add Texts" box (you can 
     copy all the abstracts for a given category at once). Click on "Reveal". 
     Adjust the number of terms to 100 using the slider below the word cloud. 
     Add our list of additional diffusion-related stop words by mousing over the
     question mark on above the word cloud, click on the revealed button 
     for "Define Other Tools", and then click on "Edit List" for stopwords. 
     Paste our list of additional stopwords while retaining the existing default
     stopwords. Note that the algorithm that creates the word cloud may not 
     place terms in the exact same spot every time.

7. The file mb2026sppq-otherjournals.txt lists the searches we 
     performed on Web of Science to count the number of total and diffusion-
     related articles appearing in select other journals. The file includes the 
     exact syntax of the specific searches we performed, the url of the search
     results, and the count of articles found. These counts are listed in 
     mb2026sppq-otherjournals.xlsx, which creates percentages
     reported in the paper. 

8. Analyses were run on a desktop with an Intel i9 processor and 32 GB of RAM 
	running Windows 11. 